if (!jsx3.lang.Class.forName("name of class")) {

/**
 * Define the <code>name of class</code> class.
 * This class inherit from <code>jsx3.gui.Block<code> GUI class.
 */
jsx3.Class.defineClass(
		"name of class",
		jsx3.gui.Block,
		null,
		function (objRoot) {
			/**
			 * This method will be called after UI file has deserialized.
			 */
			objRoot.prototype.onAfterDeserialize = function() {
			
			}

		});
}